JP2001247509A - Method of producing 2, 3, 5, 6-tetrachloro-1, 4- benzenedicarboxylic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing the subject compound as precursor of 2, 3, 5, 6-tetrachloro-1, 4-benzenedicarboxylic acid dimethyl ester which is useful as a herbicide. SOLUTION: This method of producing the subject compound is characterized by heating at a temp of 110-190 deg.C a combination of 2, 2, 5, 6-tetrachloro-1, 4-benzenedicarboxamide with sulfuric acid 10.27-14.44 in acidity function (-H0) in the presence of water in a quantity short of the theoretical level for hydrolysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid. More specifically, the present invention relates to a method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid with a reduced production of reaction by-products compared to the conventional method. The present invention relates to a method for producing 5,6-tetrachloro-1,4-benzenedicarboxylic acid.

[0002]

Technical background of the invention 2,3,5,6-tetrachloro-
1,4-Benzenedicarboxylic acid dimethyl ester is used in large quantities as an agricultural and horticultural herbicide. Conventionally, 2,
As a method for producing 3,5,6-tetrachloro-1,4-benzenedicarboxylic acid dimethyl ester, benzene-
Chlorinating 1,4-dicarbonyl chloride to give 2,
A method is known in which 3,5,6-tetrachloro-1,4-benzenedicarbonyl chloride is converted to methyl ester using methanol. However, this method has a problem that a large amount of by-products such as hexachlorobenzene is generated.

Therefore, there is a need for a method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid dimethyl ester having a low impurity content such as hexachlorobenzene. On the other hand, as a method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid dimethyl ester which does not generate hexachlorobenzene, 2,3,5,6-tetrachloroethylene which can be easily obtained industrially is used. Water is added to chloro-1,4-benzenedicarbonitrile to synthesize 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide,
Next, a method of producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid from the 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and esterifying it is considered. Can be

In general, a method for producing carboxamide by adding water to nitrile in sulfuric acid and a method for producing carboxylic acid by hydrolyzing carboxamide in sulfuric acid are well known. However, 2, 3, 5,
6-tetrachloro-1,4-benzenedicarboxamide could not be easily hydrolyzed, but 2,3,5,6-
Tetrachloro-1,4-benzenedicarboxamide,
It has been found that when heated to a temperature of 220 ° C. or more in concentrated sulfuric acid, hydrolysis occurs. However, when 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide is hydrolyzed under such severe conditions, an undesired side reaction such as decarboxylation or sulfonation occurs, and the desired compound is obtained. 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid could not be obtained in high yield.

Therefore, if 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide can be efficiently produced from 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide. If a new method emerges, its industrial value will be extremely large.

[0006]

SUMMARY OF THE INVENTION The present invention relates to 2,3,5,2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid dimethyl ester precursors useful as agricultural and horticultural herbicides.
An object of the present invention is to provide a method for producing 6-tetrachloro-1,4-benzenedicarboxylic acid. For more information,
2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile or 2,3,5,6-tetrachloro-
Starting from 1,4-benzenedicarboxamide, 2,
An object of the present invention is to provide a method capable of efficiently producing 3,5,6-tetrachloro-1,4-benzenedicarboxylic acid without producing by-products as compared with the conventional method.

[0007]

SUMMARY OF THE INVENTION The process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid according to the present invention comprises:
2,3,5,6-tetrachloro-1,4-benzenedicarboxamide is converted to 2,3,5,6-tetrachloro-1,
110 ° C. in the presence of sulfuric acid or fuming sulfuric acid containing less than the stoichiometric hydrolysis of 4-benzenedicarboxamide.
It is characterized in that it is heated at a temperature of from 190 to 190 ° C.

Further, the method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid according to the present invention is directed to 2,3,5,6-tetrachloro-1,4-benzenedicarboic acid. 2,3,5,6-tetrachloro-
2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile in the presence of sulfuric acid or fuming sulfuric acid containing less than the stoichiometric amount required to produce 1,4-benzenedicarboxylic acid Is heated at a temperature of 110 ° C. to 190 ° C.

Further, the acidity function (-H ₀ ) of the sulfuric acid containing sulfuric acid or fuming sulfuric acid is 10.27 to 14.44. According to the present invention, 2,3,5,6-tetrachloro-1,4 which is industrially easily available
2,3,5,6-tetrachloro- which can be prepared directly from benzenedicarbonitrile or easily therefrom
1,4-benzenedicarboxamide as a precursor,
By heating at a temperature of 110 ° C to 190 ° C in the presence of sulfuric acid or fuming sulfuric acid containing less than the stoichiometric hydrolysis value, 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is converted to Obtainable. According to the present invention,
Since the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide proceeds under mild conditions, side reactions are less likely to occur. Therefore, based on the present invention, 2,3,5,6-tetrachloro-1,4-
Benzenedicarboxylic acid can be easily produced with higher yield than before.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The process for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid according to the present invention will be described with reference to 2,3,5,6-tetrachloro-1,4-benzene. When prepared from dicarboxamide,
The method for producing from 5,6-tetrachloro-1,4-benzenedicarbonitrile will be specifically described below. 2,3,5,6-tetrachloro-1,4-benzenedica
From ruboxamide to 2,3,5,6-tetrachloro-1,
Production of 4-benzenedicarboxylic acid <raw material 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide> 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide , 3,5
It may be prepared from 6-tetrachloro-1,4-benzenedicarbonitrile. 2,3,5,6-tetrachloro-
1,4-benzenedicarbonitrile is industrially produced in large quantities as a raw material for pharmaceuticals, agricultural and horticultural insecticides (generic name: tefluthrin, trade name: Force), or industrial chemicals, and must be obtained at low cost. Can be. 2,3,5,6
The reaction from -tetrachloro-1,4-benzenedicarbonitrile to 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide proceeds easily and quantitatively under acidic conditions. <Hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide>
The hydrolysis of 5,6-tetrachloro-1,4-benzenedicarboxamide to 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is carried out by using 2,3,3
The reaction is performed using 5,6-tetrachloro-1,4-benzenedicarboxamide, concentrated sulfuric acid or fuming sulfuric acid, and water. Conditions that influence the reaction efficiency include, in addition to the concentration of the reactants, temperature, pressure, reaction time, and the like. These conditions are appropriately set alone or in combination.

[Concentrated sulfuric acid or fuming sulfuric acid] The concentration of concentrated sulfuric acid used has a direct effect on the reaction efficiency of temperature and time and the yield of the desired product. In the present invention, it is considered that concentrated sulfuric acid functions as a catalyst in the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and supplies water necessary for the reaction. As a first step in the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide, a proton begins to attach to its carboxamide group, followed by a water displacement reaction.

Therefore, in the above-mentioned hydrolysis, a preferred concentration of the concentrated sulfuric acid to be used is selected in consideration of the proton donating ability of the concentrated sulfuric acid and the amount of water existing before and during the reaction. In the present invention, concentrated sulfuric acid containing an amount of water smaller than the stoichiometric hydrolysis value is used. For example, concentrated sulfuric acid containing almost no water or a mixed acid of sulfuric acid and fuming sulfuric acid is suitable as a solvent for the above-mentioned hydrolysis.

The protonation ability of concentrated sulfuric acid can be represented by an acidity function, which can be measured using a Hammett indicator. For example, 95% acidity function (-H ₀₎ of sulfuric acid is 9.73. In this sulfuric acid,
Hydrolysis of 3,5,6-tetrachloro-1,4-benzenedicarboxamide requires long-time heating at a temperature higher than at least 180 ° C. 100% acidity function concentrated sulfuric acid (-H ₀₎ is 11.94, acidity function (-H ₀₎ value of the mixed acid of oleum sulfuric acid is higher than 11.94. In the present invention, the acidity function (−H ₀ ) is 10.27.
To 14.44, and using concentrated sulfuric acid having such an acidity function, 110 ° C. to 190 ° C.
The hydrolysis proceeds efficiently within the range of. Furthermore, acidity function (-H ₀₎ is preferably in the range of 10.57 to 13.00.

The amount of concentrated sulfuric acid or fuming sulfuric acid is not particularly limited. However, considering the necessity of maintaining good stirring of the solution during the reaction and the productivity per batch, 2,3,5,6
-2 to 10 parts by weight, particularly preferably 2.5 to 6 parts by weight, per part by weight of tetrachloro-1,4-benzenedicarboxamide. [Water involved in the reaction] In theory, hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide requires 2 moles of water. However, as described later, if 2 mol or more of water is present before the reaction, the hydrolysis becomes extremely difficult, and heating at a high temperature, for example, 220 ° C. or more is required to advance the reaction. On the other hand, in the present invention, 2,3,5,2,5,6-tetrachloro-1,4-benzenedicarboxamide is obtained under the condition that the amount of water is smaller than the stoichiometric value of hydrolysis. 6-tetrachloro-
Hydrolysis of 1,4-benzenedicarboxamide is performed. By doing so, the above reaction is performed at 110 to 190
It can be performed in the range of ° C. Specifically, the amount of water present before the reaction may be less than 2 moles of the stoichiometric hydrolysis value, and the smaller the amount of water, the more desirable. As a particularly preferable condition, it is sufficient that the amount of water is a very small amount close to 0 mol. Regarding the water remaining in the sulfuric acid, for example, when fuming sulfuric acid is added, as shown in the following formula, H ₂
The reaction proceeds to the left where SO ₄ is generated, and the amount of water becomes a very small amount close to 0 mol.

[0015]

Embedded image

On the other hand, even with pure sulfuric acid, at equilibrium,
It contains many chemical species, and it is thought that water molecules are present even though they are close to trace amounts. Therefore, it is considered that water generated by the decomposition of sulfuric acid that proceeds to the right in the above-mentioned equilibrium equation (IV) is supplied to the reaction. As in the present invention, in concentrated sulfuric acid or fuming sulfuric acid,
It is not known at all that the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide proceeds.

A preferred reaction condition at the start of the reaction or in the middle of the reaction to accelerate the hydrolysis at 190 ° C. or lower is that a very small amount of water is present. Therefore, as described above, it is desirable to use 2 to 10 parts by weight of concentrated sulfuric acid or fuming sulfuric acid with respect to 1 part by weight of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide. [Temperature] The temperature required for the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide varies remarkably depending on the water contained in the sulfuric acid as described above.
Therefore, when the above compound is hydrolyzed in sulfuric acid set in the present invention, it is preferably from 110 ° C to 190 ° C, more preferably from 120 ° C to 185 ° C, and still more preferably from 13 ° C to 185 ° C.
A temperature range from 0 ° C to 180 ° C is desirable. Under such temperature conditions, hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide proceeds rapidly,
The yield of 3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is also high. Conversely, if a large amount of water is present before or during the reaction, the hydrolysis does not proceed practically quickly at a temperature of 190 ° C. or less. Under these conditions, it is necessary to heat to a severe temperature, that is, 220 ° C. or higher to maintain the reaction. Further, at such a high temperature, the generated 2,3,5,6-tetrachloro-1,4-
It is not always the case that the desired compound is produced without undesirable side reactions such as decarboxylation or sulfonation of benzenedicarboxylic acid.

In practice, heating to 220.degree.
In the production method in which tetrachloro-1,4-benzenedicarboxamide is hydrolyzed in sulfuric acid, a few percent by-products such as a decarboxylation reaction are generated, and the by-products are insufficient as an agricultural chemical substance or an intermediate for an agricultural chemical. It has been found that only pure 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid can be obtained. As a further problem, equipment capable of heating to 220 ° C. or higher using sulfuric acid is extremely special and expensive equipment, and it is difficult to produce the target compound at low cost.

Accordingly, in the hydrolysis of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide, the reaction is carried out in concentrated sulfuric acid or fuming sulfuric acid containing less than the stoichiometric hydrolysis value. Is desirable from the viewpoint that hydrolysis can be carried out at a relatively low temperature and at a practical production level. [Reaction time] The reaction time depends on the temperature and the amount of water as described above. At the beginning of the reaction, the amount of water is adjusted to a minute amount, and if the reaction temperature is in the range of 110 to 190 ° C., the reaction time is within 5 minutes to 24 hours, which is convenient for industrial production. When the temperature is lowered to less than 110 ° C., the reaction takes a longer time, and the practicability is low. [Reaction progress] 2,3,5,6-tetrachloro-1,4-
In the hydrolysis of benzenedicarboxamide in sulfuric acid,
2,3,5,6-Tetrachloro-1,4-benzenedicarboxylic acid is generated and, after the reaction, precipitates out of the reaction system. Further, as the hydrolysis proceeds, the water in the formula (IV) is tilted to the right to produce water in order to supplement the consumed water. The water generated by the decomposition of the sulfuric acid is further consumed as a reactant. An amount of SO _{3 that} is not considered to be directly involved in the reaction is newly generated in an amount corresponding to the amount of the consumed water. In the present invention, the reaction is performed in an open system, and the reaction proceeds under normal pressure. In conjunction with the hydrolysis, but SO ₃ to produce during the reaction as represented by the formula (IV) is liberated, because the SO ₃ for open system leaves the system, more hydrolysis easily proceeds Become. 2,3,5,6-tetrachloro-1,4-benzenedica
2,3,5,6-tetrachloro- from rubonitrile
Production of 1,4-benzenedicarboxylic acid According to the present invention, 2,3,5,6-tetrachloro-1,
When 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is produced from 4-benzenedicarbonitrile, 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile is also used. From 110 ° C. to 190 ° C. in the presence of sulfuric acid or fuming sulfuric acid containing less than the stoichiometric amount required to produce 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid from It is preferred to heat with.

That is, from 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile,
In the reaction to 5,6-tetrachloro-1,4-benzenedicarboxamide, 2 mol of water is consumed per 1 mol of the carbonitrile compound, and 2,3,5,6-tetrachloro-1,4- From benzenedicarboxamide, 2,
Hydrolysis to 3,5,6-tetrachloro-1,4-benzenedicarboxylic acid consumes 2 moles of water per 1 mole of the carboxamide compound. Therefore, theoretically, 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile is converted to 2,3,5,6-tetrachloro-
The amount of water required to produce 1,4-benzenedicarboxylic acid is a total of 4 moles.

However, according to the present invention, 2, 3, 5, 6
The amount of water required to carry out the reaction from -tetrachloro-1,4-benzenedicarbonitrile to 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is
From 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile to 2,3,5,6-tetrachloro-1,
The amount of water may be less than the stoichiometric value of 4 moles required to produce 4-benzenedicarboxylic acid.

[0022]

According to the present invention, an inexpensive 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile is used as a raw material in an amount of water smaller than the stoichiometric hydrolysis value. A simple operation of hydrolyzing in sulfuric acid (preferably sulfuric acid containing fuming sulfuric acid) in the presence of acetic acid gives 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid useful as a herbicide precursor. Acids can be produced in high yields. Further, in the presence of water having a stoichiometric value or more, 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide which does not hydrolyze unless heated to a high temperature of 220 ° C. or more in sulfuric acid. According to the method of the present invention,
2,3,5,6-Tetrachloro-1,4-benzenedicarboxylic acid can be efficiently produced without side reactions under mild reaction conditions of 0 ° C to 190 ° C.

[0023]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to comparative examples and examples. However, these are merely examples for explanation, and the scope of the present invention is defined by the appended claims. , And is not limited by the following description.

[0024]

Example 1 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (Compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 96.3 were added to a reactor.
12.43 g of sulfuric acid (containing 0.0256 mol of water) and 26% fuming sulfuric acid 5.
A total of 17.65 g was charged with 22 g (containing 0.017 mol of SO ₃ ), heated to 180 ° C. under normal pressure, and hydrolyzed for 6 hours. The water that was present before the reaction was
_Since the water in ₃ and sulfuric acid was changed to sulfuric acid as shown in the formula (IV), the amount was 0.0086 mol. After completion of the reaction, the precipitated crystals are filtered, and the obtained crystals are dried by washing with water,
2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid was obtained. Yield: 5.8 g (95% isolated yield). IR (KBr): 770, 795, 875, 124
0, 1330, 1355, 1435, 1640, 17
05, 2470 cm ^-1 infrared spectrum was measured using potassium bromide.

[0025]

Example 2 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (Compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 96.3 were added to a reactor.
17.64 g of 10.82 g of 26% sulfuric acid and 6.82 g of 26% fuming sulfuric acid were charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1. After completion of the reaction, the same treatment as in Example 1 was performed, and
3,5,6-Tetrachloro-1,4-benzenedicarboxylic acid was obtained. Yield: 5.9 g (97% isolated yield). IR (KBr): same as in Example 1

[0026]

Example 3 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (Compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 96.3 were added to a reactor.
17.65 g of 4.64 g of 26% sulfuric acid and 13.01 g of 26% fuming sulfuric acid were charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1. After completion of the reaction, the same treatment as in Example 1 was performed, and
3,5,6-Tetrachloro-1,4-benzenedicarboxylic acid was obtained.

Yield: 4.1 g (68% isolated yield). IR (KBr): same as in Example 1

[0028]

Example 4 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 98.0
% Sulfuric acid was charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1. After completion of the reaction, the same treatment as in Example 1 was performed, and 2,3,5,6-tetrachloro-1,4
-Benzenedicarboxylic acid was obtained.

Yield: 5.8 g (95% isolated yield). IR (KBr): same as in Example 1

[0030]

Example 5 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 99.9
17.65 g of 9% sulfuric acid was charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1. After completion of the reaction, the same treatment as in Example 1 was performed, and 2,3,5,6-tetrachloro-1,4
-Benzenedicarboxylic acid was obtained.

Yield: 5.5 g (90% isolated yield). IR (KBr): same as in Example 1

[0032]

Comparative Example 1 2,3,5,6-tetrachloro-1,4-
From benzenedicarboxamide (compound 1) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 6.04 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide and 95.0 were added to a reactor.
% Sulfuric acid was charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1, but the desired 2,3,5,6-
No crystals of tetrachloro-1,4-benzenedicarboxylic acid were precipitated. Yield: 0 g (0% isolated yield).

[0033]

Example 6 2,3,5,6-tetrachloro-1,4-
From benzenedicarbonitrile (compound 3) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 5.32 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile was placed in a reactor, and 90.0
A total of 17.65 g of 11.06 g of 26% sulfuric acid and 6.59 g of 26% fuming sulfuric acid were charged and heated at 160 ° C. under normal pressure to hydrolyze for 3 hours. After completion of the reaction, the precipitated crystals were filtered and washed with water, and the obtained crystals were dried to obtain 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid. Yield: 5.9 g (97% isolated yield). IR (KBr): same as in Example 1

[0034]

Comparative Example 2 2,3,5,6-tetrachloro-1,4-
From benzenedicarbonitrile (compound 3) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 5.32 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile was placed in a reactor, and 90.0
% Sulfuric acid was charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1, but the desired 2,3,5,6-
No crystals of tetrachloro-1,4-benzenedicarboxylic acid were precipitated.

Yield: 0 g (0% isolated yield).

[0036]

Comparative Example 3 2,3,5,6-tetrachloro-1,4-
From benzenedicarbonitrile (compound 3) to 2,3
Preparation of 5,6-tetrachloro-1,4-benzenedicarboxylic acid (compound 2) 5.32 g (0.02 mol) of 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile was placed in a reactor, and 90.0
% Sulfuric acid was charged and hydrolyzed under normal pressure at the temperature and reaction time shown in Table 1. After completion of the reaction, the same treatment as in Example 6 was performed, and 2,3,5,6-tetrachloro-1,4
-Benzenedicarboxylic acid was obtained. Yield: 5.9 g (97% isolated yield) IR (KBr): same as in Example 1 Table 1 shows the starting material in a given amount of sulfuric acid in the above Examples 1 to 6 and Comparative Examples 1 to 3. 0.02 mol of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide (compound 1) or 0.02 mol of 2,3
By reacting 5,6-tetrachloro-1,4-benzenedicarbonitrile (compound 3) at a predetermined temperature and reaction time, 2,3,5,6-tetrachloro-1,4-
The result of synthesizing benzenedicarboxylic acid (Compound 2) is shown.

[0037]

[Table 1]

2,3,5,6-tetrachloro-1,4-
In the hydrolysis of benzenedicarboxamide, as shown in Example 4 or Example 5, when the amount of water in sulfuric acid was reduced to the minimum, heating at 180 ° C. or 130 ° C. for 7 hours or 27 hours As a result, the target product 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid was efficiently produced.

In Examples 1 to 3, 2, 3, 5, 6
-Tetrachloro-1,4-benzenedicarboxamide,
The above-mentioned hydrolysis occurs in sulfuric acid containing fuming sulfuric acid even without adding 2 moles of water corresponding to the theoretical amount to 1 mole from the outside, and the reaction proceeds at a temperature of 180 ° C. or less. 2,3,5,6-tetrachloro-1,4-
Benzenedicarboxylic acid was formed.

However, as shown in Comparative Example 1, 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide was used in 95% sulfuric acid (acidity function, 9.73) in 180%.
℃, and reacted for 24 hours, 2,3,5,6-
No tetrachloro-1,4-benzenedicarboxylic acid was formed. Therefore, according to the present invention,
When hydrolyzing 5,6-tetrachloro-1,4-benzenedicarboxamide, the reaction proceeds in the presence of sulfuric acid or fuming sulfuric acid containing a smaller amount of water than the stoichiometric amount of hydrolysis, and the reaction proceeds under such conditions. Below, the required temperature can be significantly reduced. A more preferred temperature range is 1
It is particularly desirable to use sulfuric acid having a temperature of 10 ° C. to 190 ° C. and containing a very small amount of water as sulfuric acid.

Next, 2,3,5,6-tetrachloro-
2,3,5,6 from 1,4-benzenedicarbonitrile
To obtain tetrachloro-1,4-benzenedicarboxylic acid, 4 moles of water is theoretically required for 1 mole of the compound. However, as shown in Example 6, in the present invention, the amount of hydrolysis is By using sulfuric acid and fuming sulfuric acid containing less than the theoretical amount of water, the mixture is heated at 160 ° C. for 3 hours to convert 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid as an objective substance into one. Efficiently obtained at the stage.

On the other hand, as shown in Comparative Example 3,
Even when heated to 220 ° C., which is the temperature at which ordinary organic compounds decompose, almost no side reaction occurs, and the desired product 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid is obtained in good yield. Generated. However, under these conditions, the reaction temperature is too high and is not at all suitable for industrial production.

Thus, starting from 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile, 2,3,5,6-tetrachloro-1,4-benzene can be obtained in one step.
To obtain benzenedicarboxylic acid, one mole of 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile is used in the presence of water in an amount smaller than the hydrolysis stoichiometric value of the reaction. And the acidity function (−H ₀ ) is 10.27 to 1
It is preferred to use sulfuric acid in the range of 4.44.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Sano 8 Ebisu-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside SDS Biotech Yokohama Plant (72) Inventor Kenichi Komatsubara Midori Tsukuba, Ibaraki 2-1-1, Kahara SDS Biotech Tsukuba Research Laboratories (72) Inventor Teruhiko Ishii 2-1-1 Midorigahara, Tsukuba, Ibaraki Pref. SDS Biotech Tsukuba F-term in the laboratory (reference) 4H006 AA02 AC46 BC10 BC17 BC34 BE03 BJ50 BM30 BS30 4H039 CA65 CD50

Claims (4)

[Claims] (1) a compound represented by the formula (I): Of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide with water having a stoichiometric value smaller than that of 2,3,5,6-tetrachloro-1,4-benzenedicarboxamide Heating at a temperature of from 110 ° C. to 190 ° C. in the presence of sulfuric acid or fuming sulfuric acid containing the following formula (II): A method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid represented by the formula: 2. An acidity function (-H) of said sulfuric acid or fuming sulfuric acid.
₀ ) is 10.27 to 14.44, The manufacturing method of Claim 1 characterized by the above-mentioned. (3) Formula (III): Is converted from 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile to 2,3,5,6-tetrachloro-1,4-benzenedicarbonitrile.
Heating at a temperature of from 110 ° C. to 190 ° C. in the presence of sulfuric acid or fuming sulfuric acid containing less than the stoichiometric amount required to produce 5,6-tetrachloro-1,4-benzenedicarboxylic acid. A method for producing 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid, which is a feature. 4. An acidity function (-H) of said sulfuric acid or fuming sulfuric acid.
4. The method according to claim 3, wherein ( ₀ ) is 10.27 to 14.44.